You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths.
Wooden i beam span table.
Conventional lumber can shrink twist and warp as the moisture found naturally in the wood evaporates.
Span tables use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads.
Floor performance is greatly influenced by the stiffness of the floor joists.
As the table shows no 2x8 s meet the span and spacing requirements but a 2x10 with an e of 1 300 000 psi and fb of 1093 psi can span 15 feet 3 inches more than enough.
I joist basics i joists are strong lightweight i shaped engineered wood structural members that meet demanding performance standards.
Joist and rafter span tables.
These span tables are based on uniform loads as noted above.
A 2x12 with an e of 800 000 psi and fb of 790 psi also works since it can span 15 feet and 10 inches.
Anything 5 and above we always at least double cripple.
On longer spans the beam may require much more bearing space as indicated by this table.
These nine beam spans are for built up beams made up of either 2x8 2x10 or 2x12 dimensional lumber nailed together as either 3 4 or 5 ply beams.
Headers beams.
For example a 3 ply 2x8 beam would use three 2x8s nailed together side by side.
Engineered wood products ewp span and size charts for bci joists.
When used as part of a flooring system wood i beam joists can help floors stay quiet over time reducing bothersome and costly callbacks.
Size selection tables headers beams.
Wood i beam blocking panels may be used in place of the 2x4.
Bci joists are specially constructed i joists with flanges made from strong versa lam laminated veneer lumber with oriented stranded board webs and approved waterproof structural adhesives providing outstanding strength and durability.
I joists are comprised of top and bottom flanges which resist bending united with webs which provide outstanding shear resistance.
The values displayed in the resulting table will show nine possible maximum beam spans for the supported length selected.
According to the 2012 irc codes any beam joist or header shall never have a bearing of less than 1 1 2.